"I don't think Valve is competing against custom built pc. Rather they are creating a platform where people can either go with a custom built pc or a pre-configured pc.

Valve has not created a new platform. They took Debian, bolted on a few minor changes, and set minimum SteamOS requirements. Nothing new to see here. If anything, it's less than impressive on its best day. This isn't about custom pc vs. pre-configured pc. It's about non-Linux gaming vs. typical Linux gaming.

"
They took a Debian (stable branch) O.S., customized and improved the graphic stack by working with nVidia and AMD then currently working ( audio performance and reductions in input latency at the operating system level. [sic]) see http://store.steampowered.com/livingroom/SteamOS

And you call this a minor staff/minor changes? I mean, without a game developer experience at this caliber(HALF LIFE), you cannot do what Valve did to their Debian based O.S. Clement Lefebvre cannot replicate Valve's works, although he is free to customized now the SteamOS to be the based of the next Mint release. SteamOS though will look like another Linux-distro on the block, but it is not something you can find at the basement. like any other distro out there. I'm tired of seeing new distro popping out in existence with the same features that you can find in every distro all over again.